Organization of cellulose synthase complexes involved in primary cell wall synthesis in Arabidopsis thaliana
Organization of cellulose synthase complexes involved in primary cell wall synthesis in Arabidopsis thaliana
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DOI：
10.1073/pnas.0706569104
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发表时间：
2007-09-25
影响因子：
11.1
通讯作者：
Vernhettes, Samantha
中科院分区：
文献类型：
--
作者：
Desprez, Thierry;Juraniec, Michal;Vernhettes, Samantha
在所有陆地植物中，纤维素是由六聚体质膜复合物合成的。间接证据表明，在维管植物中，参与初生壁合成的复合物含有三种不同的纤维素合成酶催化亚基（CESA）。在这项研究中，我们表明，CESA 3和CESA 6融合GFP表达在相同的细胞，并在同一时间在下胚轴的黄化幼苗和迁移速度相当沿着线性轨迹在细胞表面。我们还表明，CESA 3和CESA 6可以从洗涤剂溶解的提取物中共免疫沉淀，它们的蛋白质水平在CESA 3、CESA 6或CESA 1的突变体中降低，并且CESA 3、CESA 6和CESA 1可以在体内物理相互作用，如双分子荧光互补所示。我们还证明了CESA 6相关的CESA 5和CESA 2与CESA 6部分但不完全冗余，并且最有可能与CESA 6竞争纤维素合成复合物中的相同位置。使用启动子-β-葡萄糖醛酸苷酶融合，我们表明，CESA 5，CESA 6和CESA 2有不同的重叠表达模式，在下胚轴和根细胞发育的不同阶段。总之，这些数据提供了证据的存在三个不同的CESA亚基在初生壁纤维素合酶复合物的结合位点，其中两个位置总是被占据CESA 1和CESA 3，而至少有三个异构体竞争的第三个位置。后三种亚型的参与可能会微调CESA复合物在不同的细胞生长阶段沉积微纤维。
In all land plants, cellulose is synthesized from hexameric plasma membrane complexes. indirect evidence suggests that in vascular plants the complexes involved in primary wall synthesis contain three distinct cellulose synthase catalytic subunits (CESAs). In this study, we show that CESA3 and CESA6 fused to GFP are expressed in the same cells and at the same time in the hypocotyl of etiolated seedlings and migrate with comparable velocities along linear trajectories at the cell surface. We also show that CESA3 and CESA6 can be coimmunoprecipitated from detergent-solubilized extracts, their protein levels decrease in mutants for either CESA3, CESA6, or CESA1 and CESA3, CESA6 and also CESA1 can physically interact in vivo as shown by bimolecular fluorescence complementation. We also demonstrate that CESA6-related CESA5 and CESA2 are partially, but not completely, redundant with CESA6 and most likely compete with CESA6 for the same position in the cellulose synthesis complex. Using promoter-beta-glucuronidase fusions we show that CESA5, CESA6, and CESA2 have distinct overlapping expression patterns in hypocotyl and root corresponding to different stages of cellular development. Together, these data provide evidence for the existence of binding sites for three distinct CESA subunits in primary wall cellulose synthase complexes, with two positions being invariably occupied by CESA1 and CESA3, whereas at least three isoforms compete for the third position. Participation of the latter three isoforms might fine-tune the CESA complexes for the deposition of microfibrils at distinct cellular growth stages.